Aqueous coating composition, its preparation method and its application

Abstract

The present invention relates to a composition comprising: a) at least one water-soluble or water-dispersible binder; and b) at least one sag control agent (SCA), comprising: b1) at least one aliphatic polyisocyanate; and b2) at least one C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, di-C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, C4-C 10 -Alkyl-substituted anilines and di-C4-C 10 The present invention also provides an aqueous coating composition comprising an SCA obtained by reacting in the presence of component a) with at least one amine selected from the group consisting of .-alkyl substituted anilines. The present invention also provides a method for preparing the coating composition of the present invention.

Description

[Technical field]

[0001] The present invention relates to an aqueous coating composition, more particularly to an aqueous coating composition for automotive finishing and refinishing. The present invention also relates to a method for preparing said coating composition. [Background technology]

[0002] One of the key requirements for automotive coatings is that they spread well when applied, but do not sag off the substrate surface afterwards. In other words, the viscosity of the coating must be kept in the right range while it is applied to the substrate surface, so that the coating layer formed is smooth and uniform. But then the viscosity of the coating must be increased to prevent it from sagging off the vertical surfaces of the substrate.

[0003] To meet these demands, rheological additives such as sag control agents (SCAs) are added to coatings. The function of SCAs is to prevent hardening, and many of the SCAs are semi-crystalline ureido-containing organic compounds with low molecular weight. These SCAs are particularly useful in solvent-based coating compositions with medium to high solids content.

[0004] On the other hand, due to increasingly stringent environmental protection regulations, water-based coatings have become more and more popular in recent years. Water-based coatings also require SCAs. However, commonly used SCAs tend to increase the content of organic solvents, which may not be suitable for water-based coatings. Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, there remains a need to prepare water-based coatings with improved rheological properties enabled by an appropriate SCA. [Means for solving the problem]

[0006] In one aspect, the present invention provides a method for producing a) at least one water-soluble or water-dispersible binder; b) at least one sag control agent (SCA); 1. An aqueous coating composition comprising: Component b) is b1) at least one aliphatic polyisocyanate; b2) C1~C 10 -Alkoxy-C1~C 10 -Alkylamines, di-C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, C4-C 10 -Alkyl-substituted anilines and di-C4-C 10 and at least one amine selected from the group consisting of -alkyl substituted anilines, in the presence of component a).

[0007] In another aspect, the present invention provides a method for preparing the aqueous coating composition of the present invention by mixing all the components.

[0008] In a further aspect, the present invention provides a coating layer formed by curing the aqueous coating composition of the present invention applied onto a substrate.

[0009] Surprisingly, it has been found that the aqueous coating compositions of the present invention have significantly improved rheological properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0011] The terms "a," "an," and "the," when used to define a term, include both the plural and the singular form of that term.

[0012] Unless otherwise stated, all percentages, parts and ratios are by weight.

[0013] Aqueous dispersion is used as a synonym for the group consisting of aqueous solutions and aqueous emulsions.

[0014] Component a) Component a) of the aqueous coating composition of the present invention comprises at least one water-soluble or water-dispersible binder, which may have functional groups reactive towards a crosslinker.

[0015] Water-soluble or water-dispersible binders commonly used for preparing aqueous coating compositions can be used as binder component a), which water-soluble or water-dispersible binders and their preparation methods are known to those skilled in the art.

[0016] Examples of water-soluble or water-dispersible binders include, but are not limited to, polyacrylate resins, polyester resins, melamine resins, polyethers, and polyurethane resins that are dissolved or dispersed in water.

[0017] Water-soluble or water-dispersible polyacrylate resins are (meth)acrylate polymers and / or copolymers. In some embodiments, (meth)acrylate polymers and / or copolymers are polymeric organic compounds synthesized from (meth)acrylates without hydroxyl functionality, (meth)acrylates with at least one hydroxyl functionality, and optionally (meth)acrylic acid and other monomers with at least one olefinic double bond. The term (meth)acrylate refers to acrylate and / or methacrylate. The term (meth)acrylic acid refers to acrylic acid and / or methacrylic acid.

[0018] Examples of the (meth)acrylate monomers excluding hydroxyl functionality include, but are not limited to, alkyl (meth)acrylates and cycloalkyl (meth)acrylates, such as C1 to C6 alkyl (meth)acrylates. 18 -alkyl(meth)acrylates and C3-C8-cycloalkyl(meth)acrylates, preferably C1-C 12In some embodiments, the alkyl (meth)acrylates excluding the hydroxyl functionality include ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, amyl acrylate, amyl methacrylate, hexyl acrylate, hexyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, 3,3,5-trimethylhexyl ... acrylate, 3,3,5-trimethylhexyl methacrylate, stearyl acrylate, stearyl methacrylate, lauryl acrylate, lauryl methacrylate, tridecyl acrylate and tridecyl methacrylate, and preferably methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, tridecyl acrylate and tridecyl methacrylate. In some embodiments, the cycloalkyl (meth)acrylate excluding the hydroxyl functionality is at least one selected from the group consisting of cyclopentyl acrylate, cyclopentyl methacrylate, isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate, and preferably cyclohexyl acrylate and cyclohexyl methacrylate.

[0019] Examples of the (meth)acrylate monomer having at least one hydroxyl functional group include, but are not limited to, hydroxyalkyl (meth)acrylates, preferably C1-C6-hydroxyalkyl (meth)acrylates, and more preferably C2-C4-hydroxyalkyl (meth)acrylates. In some embodiments, the hydroxyalkyl (meth)acrylate having at least one hydroxyl functional group is at least one selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 3-hydroxybutyl acrylate, 3-hydroxybutyl methacrylate, and preferably 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.

[0020] The polyacrylate resin may optionally include, in the form of monomer units, acrylic acid, methacrylic acid, or any combination thereof as a comonomer, in which case the polyacrylate resin may include a free carboxylic acid, preferably acrylic acid.

[0021] The polyacrylate resin may optionally include, in the form of a monomer unit, a monomer having at least one olefinic double bond. Examples of these monomers include, but are not limited to, vinyl aromatic hydrocarbons. In some embodiments, the monomer is at least one selected from the group consisting of styrene, vinyl toluene, alpha-methylstyrene, amides or nitriles of (meth)acrylic acid, vinyl esters, and vinyl ethers, and preferably from the group consisting of styrene, amides or nitriles of (meth)acrylic acid, vinyl esters, and vinyl ethers.

[0022] There is no particular limitation on the molecular weight of the polyacrylate resin. Preferably, the number average molecular weight of the polyacrylate resin is 1,000 to 10,000 g / mol, and more preferably, 1,500 to 5,000 g / mol. Alternatively, the mass average molecular weight of the polyacrylate resin is preferably 3,000 to 20,000 g / mol, and more preferably, 5,000 to 12,000 g / mol.

[0023] In some embodiments, the polyacrylate resin may have an acid value of 10 to 200 mg KOH / g, preferably 20 to 100 mg KOH / g, and more preferably 30 to 50 mg KOH / g.

[0024] In some embodiments, the polyacrylate resin may have a hydroxyl number of 50 to 300 mg KOH / g, preferably 60 to 240 mg KOH / g, and more preferably 80 to 200 mg KOH / g.

[0025] Besides commercially available polyacrylate resins, it is also possible to use prepared (meth)acrylate (co)polymers. Methods for preparing said (meth)acrylate (co)polymers are known to those skilled in the art, for example free radical initiated (co)polymerization in bulk, solution, emulsion or microemulsion, continuously or batchwise, at atmospheric or elevated pressure in stainless steel reactors, stirred tanks, autoclaves, tube reactors, loop reactors or Taylor reactors, at temperatures between 50°C and 200°C, preferably between 80°C and 180°C, and more preferably between 100°C and 150°C. Examples of initiators for free radical (co)polymerization are at least one selected from the group consisting of dialkyl peroxides, such as di-tert-butyl peroxide or dicumyl peroxide, hydroperoxides, such as cumene hydroperoxide or tert-butyl hydroperoxide, or peroxyesters, such as tert-butyl peroxybenzoate, tert-butyl peroxypivalate, tert-butyl peroxy-3,5,5-trimethylhexanoate or tert-butyl peroxy-2-ethylhexanoate, peroxodicarbonates, potassium, sodium or ammonium peroxodisulfates, azo initiators, such as azobisisobutyronitrile, or CC cleavage initiators, such as benzpinacol silyl ethers.

[0026] Water-soluble or water-dispersible polyester resins are known to those skilled in the art and can be prepared by reacting a polyhydric alcohol and a polycarboxylic acid or anhydride.

[0027] Preferably, the polyester resin has an average condensation degree of 10 to 25. The condensation degree means the number of repeating units in the polyester resin obtained by the condensation reaction.

[0028] Preferably, the polyester resin has a maximum acid number of 30 and a maximum hydroxyl number of 150.

[0029] The acid component for synthesizing the polyester resin is a saturated or unsaturated aliphatic and / or alicyclic and / or aromatic polybasic carboxylic acid, preferably di-, tri- and tetracarboxylic acid having 2 to 14, and more preferably 4 to 12 carbon atoms, or an esterifiable derivative thereof (e.g., anhydride or ester). Examples include, but are not limited to, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydro- and hexahydrophthalic anhydride, endomethylenetetrahydrophthalic acid, succinic acid, glutaric acid, sebacic acid, azelaic acid, trimellitic acid, trimellitic anhydride, pyromellitic anhydride, fumaric acid and maleic acid. Phthalic anhydride is the most widely used acid component. The polyester resin should contain fumaric and maleic acid radicals in an amount of 20 mol % or less based on the total number of polycarboxylic acid radicals for condensation.

[0030] Said polyhydric alcohols for synthesizing the polyester resins are aliphatic and / or cycloaliphatic and / or aromatic aliphatic alcohols having 1 to 15, and preferably 2 to 6, carbon atoms and 1 to 6, and preferably 1 to 4, hydroxyl groups bonded to non-aromatic carbon atoms, such as glycols, e.g. ethylene glycol, propane-1,2- and propane-1,3-diol, butane-1,2-, -1,3- and -1,4-diol, 2-ethylpropane-1,3-diol, 2-ethylhexane-1,3-diol, neopentyl glycol, 2,2-trimethylpentane-1,3-diol, hexane-1,6-diol, cyclohexane-1,2- and -1,4-diol, 1,2- and 1,4-bis(hydroxymethyl) Cyclohexane, bis(ethylene glycol) adipate, ether alcohols such as diethylene glycol and triethylene glycol, dipropylene glycol, dimethylolpropionic acid, oxaalkylated bisphenols with two C2-C3-hydroxyalkyl groups, perhydrogenated bisphenols, butane-1,2,4-triol, hexane-1,2,6-triol, trimethylolethane, trimethylolpropane, trimethylolhexane, glycerol, pentaerythritol, dipentaerythritol, mannitol and sorbitol, chain-end monohydric alcohols with 1 to 8 carbon atoms such as propanol, butanol, cyclohexanol and benzyl alcohol, hydroxypivalic acid. The most widely used alcohols are glycerol, trimethylolpropane, neopentyl glycol and pentaerythritol.

[0031] The polyester resins may also be modified with monocarboxylic acids and monohydric alcohols.

[0032] Examples of monocarboxylic acids include saturated or unsaturated fatty acids, benzoic acid, p-tert-butylbenzoic acid, hexahydrobenzoic acid and abuletic acid.

[0033] Examples of monohydric alcohols include methanol, propanol, cyclohexanol, 2-ethylhexanol, and benzyl alcohol.

[0034] It is also possible to replace 25 mol % or less of the ester bonds with urethane bonds.

[0035] Water-soluble or water-dispersible melamine resins are known to those skilled in the art. The melamine resins are etherified melamine / formaldehyde. Besides the degree of condensation, the water solubility of the melamine resin depends on the etherified component. The melamine resin is preferably melamine etherified with methanol. Melamine etherified with butanol can be dispersed in water by adding a solubilizer.

[0036] Examples of water-soluble or water-dispersible polyethers include linear or branched poly(oxyalkylene) glycols, preferably linear or branched poly(oxypropylene) glycols, having a mass average molecular weight of 400 to 1,000, preferably 600 to 900.

[0037] Preferably, the water-soluble or water-dispersible polyurethane resin is a polyurethane resin as disclosed in German Patent No. 3,545,618 and US Pat. No. 4,423,179.

[0038] The water-soluble or water-dispersible binder may comprise a reactive or non-reactive resin. The binder may be cured by evaporation of the solvent, crosslinking via embedded functional groups or by an added crosslinking agent. Crosslinking occurs, for example, by ionic and / or radical polymerization, polycondensation and / or polyaddition reactions. Groups in the binder for crosslinking are, for example, hydroxyl groups, blocked hydroxyl groups, blocked isocyanate groups, acetoacetyl groups, (meth)acryloyl groups, allyl groups, epoxide groups, carboxyl groups, carbamate amine groups and blocked amine groups.

[0039] To obtain sufficient water solubility, the binder can be modified to become more hydrophilic. The binder can be modified to be ionic (anionic and / or cationic) or non-ionic. Anionic or non-ionic modification is preferred. Anionic modification can be achieved, for example, by incorporating carboxyl or sulfonic acid groups which are at least partially neutralized by a base. Examples of said bases are tertiary amines, such as trimethylamine, triethylamine, dimethylethylamine, dimethylbutylamine, N-methylmorpholine, dimethylethanolamine and dimethylisopropanolamine. Non-ionic modification can be achieved, for example, by incorporating polyethylene oxide units. Alternatively or in addition, emulsifiers can be used to increase hydrophilicity.

[0040] component b) The coating composition according to the present invention comprises at least one SCA (sag control agent). The SCA is selected from at least one aliphatic polyisocyanate b1) and a C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, di-C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, C4-C 10 -Alkyl-substituted anilines and di-C4-C 10 -alkyl-substituted anilines, in the presence of component a).

[0041] Any suitable aliphatic polyisocyanate b1) can be used for the preparation of the SCA. For example, any aliphatic polyisocyanate with an NCO functionality of 2.0 to 5.0 can be used. The polyisocyanate has 3 to 40, and preferably 4 to 20 carbon atoms. It is preferred to use symmetric aliphatic diisocyanates and / or their oligomers, such as symmetric diisocyanates and / or trimers of symmetric diisocyanates.

[0042] Other examples of diisocyanates include, but are not limited to, tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, and oligomers of diisocyanates such as dimeric and / or trimeric derivatives of diisocyanates, e.g., uretdione, isocyanurate and biuret analogs. Polyisocyanates may have carbodiimide, allophanate, urethane and urea groups. Preferably, the SCA includes oligomers of hexamethylene-1,6-diisocyanate, and more particularly trimers of hexamethylene-1,6-diisocyanate. These polyisocyanates can be used alone or in random combinations.

[0043] The components b2) used in the preparation of SCAs are C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, di-C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, C4-C 10 -Alkyl-substituted anilines and di-C4-C 10 from the group consisting of C1-C6-alkoxy-C2-C6-alkylamines, di-C1-C6-alkoxy-C2-C6-alkylamines, C4-C8-alkyl substituted anilines and di-C4-C8-alkyl substituted anilines, and more preferably from the group consisting of C1-C4-alkoxy-C2-C4-alkylamines and C4-C6-alkyl substituted anilines.

[0044] C1~C 10Examples of -alkyloxy include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, isobutoxy and tert-butoxy, pentoxy, isopentoxy, hexoxy, heptoxy, octoxy and decyloxy, preferably methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, isobutoxy and tert-butoxy, pentoxy, isopentoxy and hexoxy, and more preferably methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, isobutoxy and tert-butoxy.

[0045] C1~C 10 Examples of -alkyl include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethyl-hexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl and their isomers, preferably ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl and n-hexyl, and more preferably ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl.

[0046] C4~C 10Examples of -alkyl include, but are not limited to, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl and isomers thereof, preferably n-butyl, sec-butyl, isobutyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, isohept .... Includes c-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl and 2-ethylhexyl, and more preferably n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl and n-hexyl.

[0047] Preferably, component b2) is selected from the group consisting of 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxybutyl-2-amine, 1,1-dimethoxy-2-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 3-(2-ethylhexyloxy)-1-propylamine, 4-n-butylaniline, 4-sec-butylaniline, 4-isobutylaniline, 4-tert-butylaniline, 4-n-pentylaniline, 4-isopentylaniline and 4-n-hexyl More preferably, the at least one selected from the group consisting of 3-methoxy-1-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 4-n-butylaniline, 4-sec-butylaniline, 4-isobutylaniline and 4-tert-butylaniline, and even more preferably, the at least one selected from the group consisting of 3-methoxy-1-propylamine, 3-ethoxy-1-propylamine, 4-n-butylaniline, 4-isobutylaniline and 4-tert-butylaniline.

[0048] To obtain the SCA by reaction of components b1) and b2), the molar ratio of amino groups of the amine to isocyanate groups of the polyisocyanate ranges from 0.7 to 1.5, preferably from 0.8 to 1.2, and more preferably from 0.9 to 1.1. Ideally, this molar ratio is 1:1.

[0049] It is essential that the SCA is prepared by reacting components b1) and b2) in an aqueous phase in the presence of component a).

[0050] The reaction between components b1) and b2) in the presence of component a) may be carried out in various ways: Option 1: Mix the amine with the water-soluble or water-dispersible binder and then add the polyisocyanate to the mixture of amine and binder. Option 2: Mix the polyisocyanate with the water-soluble or water-dispersible binder and then add the amine to the polyisocyanate / binder mixture. Option 3: Mix a mixture of a water-soluble or water-dispersible binder and an amine with a mixture of a water-soluble or water-dispersible binder and a polyisocyanate. Option 4: The amine and polyisocyanate are mixed simultaneously with the water-soluble or water-dispersible dilutable binder.

[0051] If necessary, the addition of the polyisocyanate and / or amine may be done in one or more steps. If option 2 or 3 is chosen, it must be ensured that the polyisocyanate does not react with the reactive groups of the binder.

[0052] Preferably, the reaction temperature is in the range of 0°C to 95°C, and more preferably 10°C to 40°C.

[0053] Components b1) and b2) may be combined in any manner, however it is preferred to add the polyisocyanate to the amine, i.e., mix component b2) with component a) and then add component b2) to the mixture of components b1) and a).

[0054] Preferably, the amine is mixed with the water-soluble or water-dispersible binder and the mixture is homogenized, and then the polyisocyanate is immediately added to the mixture with stirring.

[0055] The SCA is measured by a rheometer and is -1 and a shear rate of 1,000 to 22,000 mPa·s, preferably 1,600 to 20,000 mPa·s, and more preferably 2,500 to 18,000 mPa·s, and -1 At a shear rate of 100° C., the viscosity is in the range of 200 to 2,000 mPa·s, preferably 400 to 1,600 mPa·s, and more preferably 500 to 1,400 mPa·s.

[0056] Ingredient c) The coating composition according to the invention may optionally comprise at least one crosslinker component c). Crosslinker component c) also includes unblocked, partially blocked and / or blocked polyisocyanates, and amino resins. The use of unblocked polyisocyanates is very particularly preferred. For the purposes of the present invention, polyisocyanates as crosslinkers are understood to mean organic compounds that contain at least two isocyanate groups. In principle, it is possible to use any organic compound that contains at least two isocyanate groups. It is also possible to use reaction products that contain isocyanate groups and are formed, for example, from polyhydric alcohols and polyamines and polyisocyanates.

[0057] It is also possible to use aliphatic or cycloaliphatic polyisocyanates, preferably diisocyanates, very preferably aliphatic diisocyanates, but especially hexamethylene diisocyanate (HDI), dimeric and / or trimeric hexamethylene diisocyanate.

[0058] Further examples of suitable polyisocyanates are isophorone diisocyanate, 2-isocyanatopropylcyclohexylisocyanate, dicyclohexylmethane 2,4'-diisocyanate or dicyclohexylmethane 4,4'-diisocyanate, diisocyanates derived from dimer fatty acids (such as those sold under the trade name DDI 1410 by Henkel), 1,8-diisocyanato-4-isocyanatomethyloctane, 1,7-diisocyanato-4-isocyanatomethylheptane or 1-iso-cyanato-2-(3-isocyanatopropyl)cyclohexane, or mixtures of these polyisocyanates.

[0059] Similarly, examples include tetramethylene 1,4-diisocyanate, cyclohexyl 1,4-diisocyanate, 1,5-dimethyl-2,4-di(isocyanatomethyl)benzene, 1,5-dimethyl-2,4-di(isocyanatoethyl)benzene, 1,3,5-trimethyl-2,4-di(isocyanatomethyl)benzene, 1,3,5-triethyl-2,4-di(isocyanatomethyl)benzene, dicyclohexyldimethylmethane 4,4'-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and diphenylmethane 4,4'-diisocyanate.

[0060] In a particularly preferred embodiment, the trimer of hexamethylene 1,6-diisocyanate is used as crosslinking agent, which is commercially available, for example, under the names Desmodur N3390 (Bayer MaterialScience) or Basonat HI190 (BASF SE).

[0061] Further examples of suitable polyisocyanates are organic polyisocyanates, in particular so-called paint polyisocyanates, which have free isocyanate groups bound to aliphatic, cycloaliphatic, araliphatic and / or aromatic groups. Preference is given to using polyisocyanates having 2 to 5 isocyanate groups and a viscosity of 100 to 10,000, preferably 100 to 5,000, and in particular 100 to 2,000 mPa·s (23°C). Optionally, the polyisocyanates may also be mixed with small amounts of organic solvents, preferably 1% to 25% by weight based on the pure polyisocyanate, in order to improve the ease of incorporation of the isocyanates and, optionally, to reduce the viscosity of the polyisocyanates to a level within the abovementioned ranges. Examples of suitable solvents to be added to the polyisocyanates include ethoxyethyl propionate, amyl methyl ketone or butyl acetate. Furthermore, the polyisocyanates may have been subjected to conventional hydrophilic or hydrophobic modifications.

[0062] Polyurethane prepolymers containing isocyanate groups can also be used and can be prepared by reaction of a polyhydric alcohol with an excess of a polyisocyanate. Other examples of polyisocyanates are those containing isocyanurate groups, biuret groups, allophanate groups, iminooxadiazinedione groups, urethane groups, urea groups and / or uretdione groups. Polyisocyanates containing urethane groups can be obtained by reacting a portion of the isocyanate groups with a polyhydric alcohol, such as trimethylolpropane and glycerol.

[0063] Further examples of isocyanates are described in "Methoden der organischen Chemie", Houben-Weyl, Volume 14 / 2, 4th Edition, Georg Thieme Verlag, Stuttgart, 1963, pages 61-70, W. Siefken, Liebigs Ann. Chem. 562, 75-136, European patent EP-A-101832 or US patents US-PS-3,290,350, UP-PS-4,130,577 and US-PS-4,439,616.

[0064] Said polyisocyanates are present in free form (unblocked) as crosslinking agent.These free polyisocyanates used in multi-component systems, especially in two-component systems, are known to those skilled in the art.In the present invention, this means that component a) and component c) are stored separately in the case of two-component systems and are mixed immediately before application.

[0065] However, blocked polyisocyanates can also be used instead. Blocked polyisocyanates are used in the context of the present invention as crosslinking agents in the case of one-component systems. This means that component a) and component c) can be stored and applied as a mixture. In contrast to free isocyanates, blocked polyisocyanates as crosslinking agents can only react with the functional groups of the binder at high temperatures. Such blocked polyisocyanates as crosslinking agents can also be used in multi-component systems, especially two-component systems.

[0066] The blocked crosslinker becomes unblocked at elevated temperatures (approximately 80° C. to 100° C.) and becomes available to react with the binder.

[0067] Examples of typical blocking agents are phenols, alcohols, oximes, pyrazoles, amines, and CH-acidic compounds, such as diethyl malonate. The blocking agent reacts with the free NCO groups of the crosslinker in the presence of a catalyst, such as dibutyltin dilaurate or tin(II) bis(2-ethylhexanoate). Blocking agents and reactions are known to those skilled in the art and are described in US4444954A. Preferably, the blocking agent is at least one selected from the group consisting of caprolactam, butanone oxime, acetone oxime, diethyl malonate, dimethylpyrazole, and phenol.

[0068] Furthermore, as crosslinking agents, amino resins such as melamine-formaldehyde resins, benzoguanamine-formaldehyde resins and urea-formaldehyde resins, and preferably melamine-formaldehyde resins, can be used. These are typically used in the form of etherification with alcohols such as methanol and / or butanol. An example of an amino resin is hexamethoxymethylmelamine. Condensation products of other amines and amides may be used, for example, aldehyde condensation products of triazines, diazines, triazoles, guanidines, guanimines, and alkyl- and aryl-substituted derivatives of these compounds, such as N,N'-dimethylurea, benzourea, dicyandiamide, formguanamine, acetoguanamine, ammeline, 2-chloro-4,6-diamino-1,3,5-triazine, 6-methyl-2,4-diamino-1,3,5-triazine, 3,5-diaminotriazole, triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine, 3,4,6-tris(ethylamino)-1,3,5-triazine, tris(alkoxycarbonylamino)triazine.Furthermore, in addition to the condensation products with formaldehyde, condensation products with other aldehydes may also be used.

[0069] The methylol groups of the amino resins can be blocked by carbamate or allophanate groups. Crosslinkers of this type are described in US 4710542 A and EP 0245700B, and in the article by B. Singh et al., "Carbamylmethylated Melamines, Novel Crosslinkers for the Coatings Industry", Advanced Organic Coatings Science and Technology Series, 1991, Vol. 13, pp. 193-207.

[0070] Such amino resins are commercially available and include, for example, brand names such as Cymel, Luwipal, Maprenal, Resimene, and Beetle.

[0071] Other Ingredients The coating composition may further comprise other ingredients such as pigments, fillers, etc. Any organic or inorganic type of color pigments and / or special effect pigments may be used in the coating composition. Examples of color pigments are titanium dioxide, micronized titanium dioxide, iron oxide pigments, carbon black, azo pigments, phthalocyanine pigments, quinacridone and pyrrolopyrrole pigments. Examples of special effect pigments are metal pigments such as aluminum or copper, interference pigments such as aluminum coated with titanium dioxide, coated mica, graphite effect pigments. Examples of fillers are silicon dioxide, barium sulfate, talcum, aluminum silicate and magnesium silicate.

[0072] Other additives commonly used in the coatings industry may also be added, such as light stabilizers, thickeners, defoamers, and wetting agents, etc. These additives are added in amounts known to those skilled in the art.

[0073] The coating composition may contain water in an amount of 10% to 60% by weight, preferably 15% to 50% by weight, and more preferably 20% to 40% by weight, and an organic solvent in an amount of 5% to 30% by weight, preferably 10% to 25% by weight, and more preferably 15% to 20% by weight, based on the total weight of the coating composition. Examples of solvents are monohydric or polyhydric alcohols, such as propanol, butanol, hexanol, glycol ethers or esters, such as diethylene glycol di-C1-C6-alkyl ethers, dipropylene glycol di-C1-C6-alkyl ethers, ethoxypropanol, butyl glycol, butyl glycol acetate, butyl glycol propionate, glycols, such as ethylene glycol, propylene glycol, N-methylpyrrolidone, and ketones, such as methyl ethyl ketone, acetone, cyclohexanone, aromatic or aliphatic hydrocarbons, such as toluene, xylene, and aliphatic C6-C 12 When an organic solvent is present, a water-miscible organic solvent is preferred.

[0074] The term "solid content" refers to the mass ratio of the residue after evaporation of the solvent to the total mass of the coating composition. The solid content of the coating composition is preferably in the range of 35% to 85% by mass, more preferably 45% to 80% by mass, and even more preferably 50% to 70% by mass, measured according to GB24409-2020.

[0075] The sagging limit of the coating composition is 30 to 75 μm, preferably 35 to 70 μm, and more preferably 40 to 65 μm.

[0076] The coating composition is prepared by mixing all the components using known equipment, such as a stirred tank, a stirred mill, an extruder, a compounder, an Ultraturrax, an in-line dissolver, a static mixer, a gear type disperser, a pressure relief nozzle and / or a microfluidizer (optionally excluding actinic radiation).

[0077] The coating composition of the present invention is preferably used for finishing or refinishing automobiles and is applied onto various substrates. Accordingly, a coating layer formed by curing the coating composition is also provided.

[0078] Application of the coating composition to the substrate can be by any method known to those skilled in the art, such as spraying, knife coating, sprinkling, pouring, dipping, impregnating, trickling or rolling. During such application, the substrate must be stationary while the coating device is moving. Alternatively, the substrate, preferably the coil, may be moving and the coating device may be stationary.

[0079] Preferably, spray application is used, such as compressed air spray (pneumatic application systems), airless spray, high speed rotary, electrostatic spray application (ESTA), optionally in combination with high temperature spray application, such as hot air spray.

[0080] Dwell time or evaporation time refers to the gap after application and before curing. During the dwell time, the coating composition levels out and the volatile solvents therein evaporate. The dwell time may be shortened by increasing the temperature and / or decreasing the atmospheric humidity, as long as no damage such as incomplete crosslinking is caused.

[0081] After the rest period is over, the coating composition can be cured by heat or NIR (near infrared radiation) by methods known to those skilled in the art, such as by heating in a forced air oven or by irradiation with IR lamps. The heat curing is carried out at temperatures between 40°C and 190°C, preferably between 50°C and 180°C, and more preferably between 120°C and 160°C, for 1 min to 10 h, preferably between 2 min to 5 h, more preferably between 3 min to 3 h, and even more preferably between 10 min to 0.5 h. For two-component coating systems, the heat curing is carried out at temperatures between 80°C and 160°C for 20 min to 1 h. And the heat curing is preferably carried out at temperatures between 100°C and 160°C for 20 min to 40 min for metal substrates, while at temperatures between 60°C and 100°C for plastic substrates for 30 min to 1 h ("low bake" method).

[0082] The coating composition can be applied directly onto the substrate to form a single coating layer, or onto a paint layer adhered to the substrate to form a multi-coating layer. The substrate is preferably metal or plastic, such as those used in the manufacture of automotive parts, such as PP (polypropylene) / EPDM (ethylene-propylene-diene copolymer), polyamide and / or ABS (acrylonitrile-butadiene-styrene copolymer).

[0083] For metal substrates, the coating is applied after the electrocoat, primer, and base coat are formed. For plastic substrates, the coating can be applied in both single and multiple coating layers, and when multiple coating layers are selected, the use of primers, base coats, top coats, etc. are known to those skilled in the art.

[0084] Embodiment The following embodiments are used to further illustrate how the present invention can be implemented.

[0085] EMBODIMENT 1 a) at least one water-soluble or water-dispersible binder; b) at least one sag control agent (SCA); 1. An aqueous coating composition comprising: Component b) is b1) at least one aliphatic polyisocyanate; and b2) C1~C 10 -Alkoxy-C1~C 10 -Alkylamines, di-C1-C 10 -Alkoxy-C1~C 10 -Alkylamines, C4-C 10 -Alkyl-substituted anilines and di-C4-C 10 - alkyl-substituted anilines, Aqueous coating compositions.

[0086] EMBODIMENT 2 Component c): The aqueous coating composition according to embodiment 1, further comprising at least one crosslinking agent.

[0087] EMBODIMENT 3 An aqueous coating composition according to embodiment 2, comprising 10% to 90% by weight, preferably 15% to 70% by weight, and more preferably 20 to 50% by weight of component a), 0.1% to 40% by weight, preferably 5% to 35% by weight, and more preferably 15% to 30% by weight of component b), and 0.1% to 70% by weight, preferably 15% to 60% by weight, and more preferably 30% to 50% by weight of component c), the mass percentage values ​​of components a), b) and c) being relative to the total mass of the aqueous coating composition.

[0088] EMBODIMENT 4 The aqueous coating composition according to any one of the preceding embodiments, wherein component a) is preferably at least one selected from the group consisting of polyacrylate resins, polyester resins, melamine resins, polyether resins and polyurethane resins.

[0089] EMBODIMENT 5 The aqueous coating composition according to embodiment 4, wherein the water-soluble or water-dispersible polyacrylate resin is preferably at least one selected from the group consisting of polymeric organic compounds synthesized from (meth)acrylates excluding hydroxyl functional groups, (meth)acrylates having at least one hydroxyl functional group, optionally (meth)acrylic acid, and other monomers having at least one olefinic double bond.

[0090] EMBODIMENT 6 The (meth)acrylate, excluding the hydroxyl functional group, is preferably a C1-C 18 from the group consisting of C1-C-alkyl (meth)acrylates and C3-C8-cycloalkyl (meth)acrylates, more preferably C1-C 12The aqueous coating composition according to embodiment 5, wherein the alkyl (meth)acrylate is at least one selected from the group consisting of C1-C6-alkyl (meth)acrylates and C3-C6-cycloalkyl (meth)acrylates, and even more preferably from the group consisting of C1-C6-alkyl (meth)acrylates and C5-C6-cycloalkyl (meth)acrylates.

[0091] EMBODIMENT 7 The aqueous coating composition according to embodiment 5, wherein said (meth)acrylate having at least one hydroxyl functional group is preferably at least one selected from the group consisting of C1-C6-hydroxyalkyl (meth)acrylates, and more preferably from the group consisting of C2-C4-hydroxyalkyl (meth)acrylates.

[0092] EMBODIMENT 8 The aqueous coating composition according to embodiment 5, wherein said monomer having at least one olefinic double bond is preferably at least one selected from the group consisting of vinyl aromatic hydrocarbons, more preferably from the group consisting of styrene, vinyl toluene and alpha-methylstyrene, and even more preferably from the group consisting of amides, nitriles, vinyl esters and vinyl ethers of styrene, acrylic acid, methacrylic acid.

[0093] EMBODIMENT 9 9. The aqueous coating composition according to any one of embodiments 4 to 8, wherein the number average molecular weight of the polyacrylate resin is from 1,000 to 10,000 g / mol, and preferably from 1,500 to 5,000 g / mol.

[0094] EMBODIMENT 10 10. The aqueous coating composition according to any one of embodiments 4 to 9, wherein the weight average molecular weight of the polyacrylate resin is from 3,000 to 20,000 g / mol, and preferably from 5,000 to 12,000 g / mol.

[0095] EMBODIMENT 11 11. The aqueous coating composition according to any one of embodiments 4 to 10, wherein the polyacrylate resin has an acid value of 10 to 200 mg KOH / g, preferably 20 to 100 mg KOH / g, and more preferably 30 to 50 mg KOH / g.

[0096] EMBODIMENT 12 12. The aqueous coating composition according to any one of embodiments 4 to 11, wherein the polyacrylate resin has a hydroxyl value of 50 to 300 mg KOH / g, preferably 60 to 240 mg KOH / g, and more preferably 80 to 200 mg KOH / g.

[0097] EMBODIMENT 13 13. The aqueous coating composition according to any one of embodiments 2 to 12, wherein the component c): crosslinker is preferably at least one selected from unblocked, partially blocked and blocked polyisocyanates and amino resins.

[0098] EMBODIMENT 14 The aqueous coating composition according to any one of embodiments 1 to 13, wherein the aliphatic polyisocyanate (b1) is preferably selected from the group consisting of symmetric aliphatic diisocyanates and oligomers of symmetric aliphatic diisocyanates.

[0099] EMBODIMENT 15 The aqueous coating composition according to embodiment 14, wherein the aliphatic polyisocyanate (b1) is at least one selected from the group consisting of tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, and a trimer of hexamethylene-1,6-diisocyanate.

[0100] EMBODIMENT 16 The aqueous coating composition according to any one of embodiments 1 to 15, wherein the amine (b2) is preferably at least one selected from the group consisting of C1-C6-alkoxy-C2-C6-alkylamines, di-C1-C6-alkoxy-C2-C6-alkylamines, C4-C8-alkyl-substituted anilines and di-C4-C8-alkyl-substituted anilines, and more preferably from the group consisting of C1-C4-alkoxy-C2-C4-alkylamines and C4-C6-alkyl-substituted anilines.

[0101] EMBODIMENT 17 The amine b2) is preferably 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxybutyl-2-amine, 1,1-dimethoxy-2-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 3-(2-ethylhexyloxy)-1-propylamine, 4-n-butylaniline, 4-sec-butylaniline, 4-isobutylaniline, 4-tert-butylaniline, 4-n-pentylaniline, 4-isopentylaniline, or 4-n-hexylaniline. 17. The aqueous coating composition according to embodiment 16, wherein the aniline is at least one selected from the group consisting of 3-methoxy-1-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 4-n-butylaniline, 4-sec-butylaniline, 4-isobutylaniline and 4-tert-butylaniline, and more preferably from the group consisting of 3-methoxy-1-propylamine, 3-ethoxy-1-propylamine, 4-n-butylaniline, 4-isobutylaniline and 4-tert-butylaniline.

[0102] EMBODIMENT 18 18. The aqueous coating composition according to any one of the preceding embodiments, wherein the molar ratio of b2): amino groups of the amine to b1): isocyanate groups of the aliphatic polyisocyanate is in the range of 0.7-1.5, preferably 0.8-1.2, and more preferably 0.9-1.1.

[0103] EMBODIMENT 19 A method for preparing an aqueous coating composition according to any one of the preceding embodiments by mixing components a), b), and, optionally, c).

[0104] EMBODIMENT 20 A coating layer formed by curing the aqueous coating composition according to any one of embodiments 1 to 18 applied onto a substrate. EXAMPLES

[0105] The following non-limiting examples are included to further illustrate various embodiments of the disclosure and are not intended to limit the scope of the disclosure.

[0106] Materials used in all examples: Desmodur N3300: Aliphatic polyisocyanate (HDI trimer), commercially available from Covestro AG. Cymel 327: Crosslinker, commercially available from Allnex. TBN-75PS: Crosslinker, blocked polyisocyanate, commercially available from Asahi Kasei Corporation. Disparlon AQ-7180: a wetting agent, commercially available from Kusumoto Chemicals. Tinuvin 400 and Tinuvin 292: Light stabilizers, commercially available from BASF.

[0107] The molecular weights of the polyacrylates (including weight average molecular weight and number average molecular weight) were determined by gel permeation chromatography (GPC): Instrument: Agilent 1200 series Eluent: 1 mol / L CH3COOH-THF Injection volume: 100μL Temperature: 35℃ Flow rate: 1.0ml / min Measurement time: 50 minutes Molecular standard: PMMA The viscosity of the SCA was measured at a shear rate of 1 s using a rheometer (Antor Paar MCR302). -1and 1,000 seconds -1 was measured.

[0108] Example 1: Synthesis of polyacrylate A A stainless steel reactor was precharged with 173.9 parts by weight of butyl glycol under atmospheric pressure with nitrogen flushed off and stirring at 100 RPM (revolutions per minute). The reactor was heated to 120°C and once the temperature stabilized, a premix of 40.2 parts by weight of tert-butyl peroxy-2-ethylhexanoate and 38.0 parts by weight of butyl glycol was charged over 4.75 hours. Approximately 15 minutes after the initiator charge, a premix of 81.5 parts by weight of styrene, 108.7 parts by weight of hydroxyethyl methacrylate, 81.5 parts by weight of tert-butyl acrylate, 81.5 parts by weight of tridecyl methacrylate, 163 parts by weight of cyclohexyl methacrylate, 24.5 parts by weight of acrylic acid, and 5.4 parts by weight of butyl glycol was charged over 4 hours. After the monomer and initiator charge, the reactor was held at 120°C for 1 hour. The reactor was then cooled to 80°C, and 11.7 parts by weight of dimethylethanolamine was charged within 5 minutes for neutralization. The reactor was held at 70°C for 30 minutes, and then 190.2 parts by weight of deionized water was charged through a dropping funnel over 1 hour. After stirring for 30 minutes, the synthesized resin was filtered through a 200um steel filter bag. The molecular weight was measured by GPC, and was found to be Mw (weight average molecular weight): 9,600 and Mn (number average molecular weight): 4,600.

[0109] Example 2: Synthesis of polyacrylate B A stainless steel reactor was precharged with 167.6 parts by weight of butyl glycol under atmospheric pressure with nitrogen flushed off and stirring at 100 RPM. The reactor was heated to 120°C. Once the temperature was stable, a premix of 40.3 parts by weight of tert-butyl peroxy-2-ethylhexanoate and 36.1 parts by weight of butyl glycol was charged over 4.75 hours. Approximately 15 minutes after the initiator charge, a premix of 26.2 parts by weight of styrene, 246.2 parts by weight of hydroxyethyl methacrylate, 65 parts by weight of tert-butyl acrylate, 66 parts by weight of tridecyl methacrylate, 131 parts by weight of cyclohexyl methacrylate, 23.6 parts by weight of acrylic acid, and 5.2 parts by weight of butyl glycol was charged over 4 hours. After the monomer and initiator charge, the reactor was held at 120°C for 1 hour. The reactor was then cooled to 80°C and 10 parts by weight of dimethylethanolamine was charged within 5 minutes for neutralization. The reactor was held at 70°C for 30 minutes, after which 194 parts by weight of deionized water was charged through a dropping funnel over 1 hour. After stirring for 30 minutes, the synthesized resin was filtered through a 200um steel filter bag. The molecular weight was measured by GPC to be Mw: 8,100 and Mn: 4,100.

[0110] Example 3: Synthesis of SCA C In a stainless steel reactor, 251 parts by weight of Polyacrylate A (solids content: 59% by weight) and 4.59 parts by weight of 3-methoxy-1-propylamine were mixed for 2 minutes at room temperature (5-40°C). A premix of 9.75 parts by weight of Desmodur N3300 and 9.11 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before the reaction was completed. The resulting SCA C was a buttery solid with an immeasurable viscosity.

[0111] Example 4: Synthesis of SCA D In a stainless steel reactor, 251 parts by weight of Polyacrylate A (solid content: 59% by weight) and 4.61 parts by weight of 3-methoxy-1-propylamine were mixed for 2 minutes at room temperature (5-40°C). A premix of 4.26 parts by weight of HDI monomer and 9.13 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before the reaction was allowed to go to completion. The viscosity of the resulting SCA D was 0.01% at a shear rate of 1 second. -1 and 1,000 seconds -1 Under these conditions, the values ​​were 17,647 and 686 MPa·s, respectively.

[0112] Example 5: Synthesis of SCA E In a stainless steel reactor, 251 parts by weight of Polyacrylate A (solid content: 59% by weight), 3.85 parts by weight of 4-butylaniline, and 10.74 parts by weight of butyl glycol were mixed for 2 minutes at room temperature (5-40°C). A premix of 4.83 parts by weight of Desmodur N3300 and 13.46 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before the reaction was completed. The viscosity of the resulting SCA E was 0.01% at a shear rate of 1 second. -1 and 1,000 seconds -1 Under these conditions, the values ​​were 6,370 and 632 MPa·s, respectively.

[0113] Example 6: Synthesis of SCA F In a stainless steel reactor, 251 parts by weight of Polyacrylate A (59% solids) and 7.81 parts by weight of 4-butylaniline were mixed for 2 minutes at room temperature (5-40°C). A premix of 4.33 parts by weight of HDI monomer and 9.27 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before allowing the reaction to go to completion. The viscosity of the resulting SCA F was 0.01% at a shear rate of 1 second. -1 and 1,000 seconds -1 Under these conditions, the values ​​were 13,129 and 1,196 MPa·s, respectively.

[0114] Example 7: Synthesis of SCA G (Comparative Example) In a stainless steel reactor, 251 parts by weight of polyacrylate A (solid content: 59% by weight), 1.58 parts by weight of ethanolamine, and 6.6 parts by weight of butyl glycol were mixed for 2 minutes at room temperature (5-40°C). A premix of 4.83 parts by weight of Desmodur N3300 and 20.20 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before the reaction was completed. The viscosity of the resulting SCA G was 0.01 g at a shear rate of 1 s. -1 and 1,000 seconds -1 Under these conditions, the values ​​were 2,952 and 537 MPa·sec, respectively.

[0115] Example 8: Synthesis of SCA H (Comparative) In a stainless steel reactor, 251 parts by weight of Polyacrylate A (59% solids) were mixed with 3.15 parts by weight of ethanolamine and 0.31 parts by weight of butyl glycol for 2 minutes at room temperature (5-40°C). A premix of 4.26 parts by weight of HDI monomer and 9.11 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before allowing the reaction to go to completion. The viscosity of the resulting SCA H was 0.01% at a shear rate of 1 second. -1 and 1,000 seconds -1 Under these conditions, the values ​​were 2,621 and 1,017 MPa·s, respectively.

[0116] Example 9: Synthesis of SCA I (Comparative Example) In a stainless steel reactor, 251 parts by weight of Polyacrylate A (solid content: 59% by weight), 3.54 parts by weight of 4-methoxybenzylamine, and 10.51 parts by weight of butyl glycol were mixed for 2 minutes at room temperature (5-40°C). A premix of 4.83 parts by weight of Desmodur N3300 and 20.20 parts by weight of butyl glycol was then added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before the reaction was completed. The viscosity of the resulting SCA I was 0.01% at a shear rate of 1 second. -1 and 1,000 seconds-1 Under these conditions, the values ​​were 7,440 and 647 MPa·s, respectively.

[0117] Example 10: Synthesis of SCA J (Comparative) In a stainless steel reactor, 251 parts by weight of Polyacrylate A (solids content: 59% by weight) and 7.07 parts by weight of 4-methoxybenzylamine were mixed for 2 minutes at room temperature (5-40°C). Next, a premix of 4.26 parts by weight of HDI monomer and 9.11 parts by weight of butyl glycol was added to the reactor under full stirring power of 2,000 RPM for 10 minutes. After addition, the mixture was stirred for an additional 10 minutes before the reaction was allowed to go to completion. The viscosity of the resulting SCA J was 0.01% at a shear rate of 1 second. -1 and 1,000 seconds -1 Under these conditions, the values ​​were 6,187 and 1,192 MPa·s, respectively.

[0118] Sagging test of water-based coating compositions The aqueous coating compositions were prepared by mixing the components listed in Table 1 with stirring at room temperature (5-40° C.).

[0119] The sagging test was carried out according to the following method: The coating compositions were sprayed with an air-powered spray onto steel panels (dimensions: 60 cm x 30 cm) covered with an electro-deposition coating (thickness: 15 μm, CG800 from BASF Coatings) to form a gradient thickness clearcoat layer. The sprayed panels were hung vertically in an oven and cured at 140°C for 20 minutes. After curing was complete, the thickness of the panel was measured at the location where sagging occurred, and the thickness of the panel at that location was recorded as the sagging value. The sagging test results for the examples are summarized in Table 1.

[0120] [Table 1]

[0121] MPA: 3-methoxy-1-propylamine, BLA: 4-butylaniline, MBA: 4-methoxybenzylamine, EA: ethanolamine Trimer: Desmodur N3300, HDI: HDI monomer

[0122] As shown in Table 1, increased sag values ​​were obtained using the aqueous coating compositions according to the embodiments of the present invention compared to the comparative examples. The higher the sag value, the less prone the coating composition is to sag.

Claims

1. a) at least one water-soluble or water-dispersible binder, b) at least one sag control agent (SCA), An aqueous coating composition comprising: Component b) is b1) at least one aliphatic polyisocyanate and b2) C １ ~C １０ -alkoxy-C １ ~C １０ -alkylamine, di-C １ ~C １０ -alkoxy-C １ ~C １０ -alkylamine, C ４ ~C １０ -alkyl-substituted aniline and di-C ４ ~C １０ obtained by reaction in the presence of component a) with at least one amine selected from the group consisting of An aqueous coating composition.

2. The aqueous coating composition according to claim 1, further comprising component c): at least one crosslinking agent.

3. 10% to 90% by mass, preferably 15% to 70% by mass, and more preferably 20% to 50% by mass of component a), 0.1% to 40% by mass, preferably 5% to 35% by mass, and more preferably 15% to 30% by mass of component b), and 0.1% to 70% by mass, preferably 15% to 60% by mass, and more preferably 30% to 50% by mass of component c), The aqueous coating composition according to claim 2, wherein the mass percentage values of components a), b) and c) are based on the total mass of the aqueous coating composition.

4. The aqueous coating composition according to any one of claims 1 to 3, wherein component a) is at least one selected from the group consisting of polyacrylate resins, polyester resins, melamine resins, polyether resins and polyurethane resins.

5. The water-soluble or water-dispersible polyacrylate resin is at least one selected from the group consisting of (meth)acrylates excluding hydroxyl functional groups, (meth)acrylates having at least one hydroxyl functional group, optionally (meth)acrylic acid, and polymer organic compounds synthesized from at least one other monomer having at least one olefinic double bond. The aqueous coating composition according to claim 4.

6. The (meth)acrylate excluding the hydroxyl functional group is C １ to C １８ -alkyl (meth)acrylate and C ３ to C ８ -cycloalkyl (meth)acrylate, preferably C １ to C １２ -alkyl (meth)acrylate and C ３ to C ６ -cycloalkyl (meth)acrylate, and more preferably C １ to C ６ -alkyl (meth)acrylate and C ５ to C ６ -cycloalkyl (meth)acrylate, and is at least one selected from the group consisting of the aqueous coating composition according to claim 5.

7. The (meth)acrylate having at least one hydroxyl functional group is C １ to C ６ -hydroxyalkyl (meth)acrylate, and preferably C ２ to C ４ The aqueous coating composition according to claim 5, which is at least one selected from the group consisting of -hydroxyalkyl (meth)acrylate.

8. The monomer having at least one olefinic double bond is at least one selected from the group consisting of vinyl aromatic hydrocarbons, preferably from the group consisting of styrene, vinyltoluene and alpha-methylstyrene, and more preferably from the group consisting of styrene, acrylate, methacrylate amides, nitriles, vinyl esters and vinyl ethers. The aqueous coating composition according to claim 5.

9. The aqueous coating composition according to claim 4, wherein the number average molecular weight of the polyacrylate resin is 1,000 to 10,000 g / mol, and preferably 1,500 to 5,000 g / mol.

10. The aqueous coating composition according to claim 4, wherein the polyacrylate resin has a mass average molecular weight of 3,000 to 20,000 g / mol, and preferably 5,000 to 12,000 g / mol.

11. The aqueous coating composition according to claim 4, wherein the polyacrylate resin has an acid value of 10 to 200 mgKOH / g, preferably 20 to 100 mgKOH / g, and more preferably 30 to 50 mgKOH / g.

12. The aqueous coating composition according to claim 4, wherein the polyacrylate resin has a hydroxyl value of 50 to 300 mgKOH / g, preferably 60 to 240 mgKOH / g, and more preferably 80 to 200 mgKOH / g.

13. The aqueous coating composition according to claim 2 or 3, wherein the component c): crosslinking agent is at least one selected from unblocked, partially blocked and blocked polyisocyanates and amino resins.

14. The aqueous coating composition according to any one of claims 1 to 3, wherein the b1): aliphatic polyisocyanate is selected from the group consisting of symmetric aliphatic diisocyanates and oligomers of symmetric aliphatic diisocyanates.

15. The aqueous coating composition according to claim 14, wherein the b1): aliphatic polyisocyanate is at least one selected from the group consisting of tetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, trimethylhexane diisocyanate and tetramethylhexane diisocyanate, and trimers of hexamethylene-1,6-diisocyanate.

16. The aforesaid b2): the amine is C １ -C ６ -alkoxy-C ２ -C ６ -alkylamine, di-C １ -C ６ -alkoxy-C ２ -C ６ -alkylamine, C ４ -C ８ -alkyl-substituted aniline and di-C ４ -C ８ -alkyl-substituted aniline, and preferably, C １ -C ４ -alkoxy-C ２ -C ４ -alkylamine and C ４ -C ６ -alkyl-substituted aniline, and is at least one selected from the group consisting of, and preferably, the aqueous coating composition according to any one of claims 1 to 3.

17. Said b2): The amine is 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxy-1-propylamine, 1-methoxybutyl-2-amine, 1,1-dimethoxy-2-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 3-(2-ethylhexyloxy)-1-propylamine, 4-n-butylaniline, 4-sec-butylaniline, 4-isobutylaniline, 4-tert-butylaniline, 4-n-pentylaniline, 4-isopentylaniline and 4-n-hexylaniline, preferably from the group consisting of 3-methoxy-1-propylamine, 3-ethoxy-1-propylamine, 3-butoxy-1-propylamine, 4-n-butylaniline, 4-sec-butylaniline, 4-isobutylaniline and 4-tert-butylaniline, and more preferably from the group consisting of 3-methoxy-1-propylamine, 3-ethoxy-1-propylamine, 4-n-butylaniline, 4-isobutylaniline and 4-tert-butylaniline, and is at least one selected therefrom, the aqueous coating composition according to claim 16.

18. b2): The molar ratio of the amino group of the amine to the isocyanate group of the aliphatic polyisocyanate in b1) is in the range of 0.7 to 1.5, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1, the aqueous coating composition according to any one of claims 1 to 3.

19. A method for preparing the aqueous coating composition according to any one of claims 1 to 3 by mixing components a), b), and optionally c).

20. A coating layer formed by curing the aqueous coating composition according to any one of claims 1 to 3 applied on a substrate.